It is generally accepted that the performance of an internal combustion engine is dependent on a number of factors that may include the operating cycle (e.g., two-stroke having 360 degrees of crankshaft rotation per cycle, four-stroke having 720 degrees of crankshaft rotation per cycle or Wankel rotary engines), the fuel type (e.g., gasoline, diesel, alcohol, liquid petroleum gas (LPG), or natural gas), the number and design of combustion chambers, the selection and control of ignition and fuel delivery systems, and the ambient conditions in which the engine operates.
Examples of design choices for a combustion chamber include choosing a compression ratio and choosing the numbers of intake and exhaust valves associated with each chamber.
With regard to ignition systems, breaker point systems and electronic ignition systems are known ignition systems. Those systems provide spark timing based on one or more operating characteristics of the engine, e.g., speed of rotation and load. In the case of breaker point systems, engine speed is frequently detected mechanically using centrifugally displaced weights and intake manifold pressure or exhaust manifold pressure is commonly used to detect engine load. In the case of electronic ignition systems, engine speed is often detected with an angular motion sensor associated with rotation of the crankshaft and engine load is frequently detected by a throttle position sensor, an intake manifold pressure sensor or a mass airflow sensor. In each case, spark timing may be fixed for a given steady operating state of the engine.
With regard to fuel delivery systems, carburetors and fuel injection systems are known. Those known systems supply a quantity of fuel, e.g., gasoline or diesel fuel and air, in accordance with the position of the throttle as set by the operator. In the case of carburetors, fuel is typically delivered by a system of orifices, known as “jets.” As examples of carburetor operation, an idle jet may supply fuel downstream of a throttle valve at engine idling speeds, and that fuel delivery may be boosted by an accelerator pump to facilitate rapid increases in engine load.
Known fuel injection systems, which can be operated electronically, generally spray a metered amount of fuel into the intake system or directly into the combustion cylinder. The fuel quantity is often determined by a controller based on the state of the engine and a data table known as a “map” or “look-up table.” The map typically includes a collection of possible values or “setpoints” for each of at least one independent variable that may be a characteristic of the state of the engine, which can be measured by a sensor connected to the controller, and a collection of corresponding control values for a dependent variable control function, such as fuel quantity.
Conventionally, factory calibrated maps are typically developed by the engine manufacturer and permanently set in an engine control unit at the factory. The manufacturers may further prevent engine operators from modifying the maps for a variety of reasons, such as the manufacturers believe that their maps provide the best engine performance, the manufacturers are concerned that an engine operator might damage the engine by specifying inappropriate control values, or the manufacturers assume that an engine operator might not have sufficient skill to properly modify a map. However, it is believed that the manufacturers have “optimized” their maps to perform best under a set of conditions that they specify. In certain cases, however, it is believed that those conditions do not match the conditions in which the engine is operated. Consequently, stock maps sometimes limit, rather than optimize, an engine's performance.
Conventional maps, furthermore, are typically created to provide fuel delivery and ignition timing suitable for the engine when operating at a steady-state. Thus, map values may not be appropriate for an engine operating in transition such as, for example, an accelerating or decelerating engine.
Further, engine performance is believed to be substantially dependent on how combustion is accomplished in the ambient conditions. The stoichiometric mass fraction ratio of air to gasoline is approximately 14.7:1. However, it is believed that ratios from about 10:1 to about 20:1 will combust, and that it is often desirable to adjust the air-fuel ratio (“AFR”) to achieve specific engine performance, such as a desired level of power output, better fuel economy, or reduced emissions. Properly calibrating the fuel delivery system of an engine to deliver the optimum AFR under all operating conditions is an important goal of many calibration efforts. It is also frequently a time consuming, difficult, and costly part of the calibration effort. Similarly, it may also be desirable to adjust ignition timing, commonly measured in degrees of crank rotation before a piston reaches top-dead-center of the compression stroke, to achieve specific engine performance, such as low fuel consumption or reduced emissions.
In the current state of the fueling art, injected engine fueling is typically based on one or an average of several engine speed and load readings taken during one or more previous engine cycles. As will be recognized, when an engine is transitioning to a higher or lower speed or load or otherwise changing operating conditions during a current combustion cycle, the operational information from those previous engine cycles is likely not to be appropriate for a current engine cycle. Thus there may be a need for systems, apparatuses, and methods for considering transitions in engine operating conditions when controlling engine combustion. There may also be a need for systems, apparatuses, and methods for predicting future engine operating conditions when controlling engine combustion and utilizing that information to provide fueling, quantity, ignition timing, exhaust gas recirculation or other components of combustion.